Development accelerators for silver halide emulsion layers



United States Patent 3 502 472 DEVELOPMENT AcELERAToRs FOR SILVER HALIDEEMULSION LAYERS Jozef Frans Willems, Wilrijk-Antwerp, Francis J eaune3,502,472 Patented Mar. 24, 1970 ice Such substances, however, cause anincrease of the free silver ion concentration of the emulsion andgreatly diminish its stability.

It is also known that an increase of sensitivity can be obtained byincorporating into the photographic material Sels, Kontich, and RobrechtJulius Thiers, Brasschaat, 5 1 th 1 1 1 1k 1 Belgium, assignors toGevaert-Agfa N.V., Mortselp0 ye y a yco a yefle 9 Polymers obtamedBelgium, 3 B el gi all company by polymerlslng alkylene oxide in thepresence of hexltol No Drawing. Filed Oct 6, 1966, Ser. No. 584,650 ringdehydration products, aliphatic alcohols, aliphatic Claims priority,application Great Britain, Oct. 11, 1965, aclds, amines, amides, andphenols (UK. patent specifica- 42,972/65 10 tions Nos. 548,019 filedMar. 19, 1941 by Kodak, 600,058 Us Cl 96 5/301/72 4 Cl filed Jan. 10,1946 and 592,676 filed Apr. 20, 1945 both mms by E. I. du Pont deNemours, 758,745 filed Jan. 6, 1954 by Raduner & Co., A. G. and 748,750filed June 28, 1954 by Kodak). ABSTRACT OF ][H E P S It is further knownthat these polyglycols and alkylene Process for P g f P g P sllvel' g yoxide polymers should possess a molecular weight of at development ofexposed llght-sensltlve silver halide 1n the least 400. In order toobtain a noticeable effect, it is in presence of compound lnlltlenclngthe sen ltome lc c arpractice necessary to use compounds having amolecular acteristics of a light-sensltlve silver halide emulsion byWeight f 1500 to 2000i and more an Increase of th pe d and/ r t gradatin. Contrary to the other known methods for increasing the sensitivity ofsilver halide emulsions such as those in which the chemical sensitizersincrease the inherent T1118 1I1Vnt1QI1 felfltes to a Process Produclflga sensitivity and those in which the cyanine dyes increase R Ph 11VeF bydevelopment of exposed the spectral absorption, it appears that thefinal sensitivity light-sensitive silver halide 111 the presence ofcompounds f the silver halide emulsion layers in which these com.1111106961113 the sellsltomefrlc. charactensflcs of a lightpounds areincorporated is higher since these compounds Sensltlve sllvflr halldeelflulslon y an 0f the exert a favourable influence on the developmentof these Speed and/Or the gradatlon- T present 1nven t10n also silverhalide layers by means of the usual developers. relates to photographicmaterlals and developing baths Consequently these compounds can beconsidered as contalnlrlg sald compounds and to a class of saidcomdevelopment accelerators. i f h h 1 f h It is also known, however,that a noticeable increase in i g e f serlljsmvlty 3. 3 5; sensitivityis only obtained with these compounds when emu Sums W can a lea y esensl p y developing in rather slow working developers of the finethroughout the whole range of the spectrum by means of d V610 er t usedin th dev 10 m m of the so-called chemical sensitizers, such as sulphurg p ype In f t 1 1 sensitizers, can be increased yet if amines or somepolytmuous one as f f amines such as diethylenetriamine,triethylenetetramine, Phenol hydroqumone or 1 eny -PY P etc. are addedto these photographic elements. (U.S. l" defelopers developmentaccijleratmg patent specification No. 734,474 filed Nov. 6, 1953 by 40@1011 mamfests Itself only y a y moderate Increase Kodak.) of the speedof the developed photographic material.

TABLE I Used bis-w-hydroxy-alkylene Reaction amines or2,3:2,3-diepoxy-N- Used dicarboxylic acid or Reaction temp,alkyldipropylamines derivative thereof time, hr. 0. Remarks CH2CH2OH H0OC(CH2)zCOOH 20 -50 Distil ofi azeotropically the formed water Compound 1in toluene. Water-soluble.

Egon-N C2H5O O C(OHQZC OO C H 8 -200 Distil ofl ethanol. Water-soluble.

CH2CH2OH Compound 2 CHQCHZOH HOOCCHZOCHZOOOH 6 -5 Distil ofiazeotropieally the formed water in anisol. Water-soluble. H3CN CHzCHzOHO 7 200-220 The f rmed water dist'ls over. Soluble in Compound OHZGHZOHHO O C (CHZMO O H Wat r in the hydroxyizhloride form.

H3CN

CHzCHzOH Compound 4...- CHiCHZOH HOOCOH=GH-COOH 3 135-40 Distilofithetormedwaterinxylene.

Water-soluble. N-CHzCH2OH CHzCHzOH Compound 5 CH CH OH HOOC(CHZ)4OOOH 8-230 The formed water distils over. Soluble in water in tolusulphonateform. H3C(CHz)gN Compound 6-... O HOOC(CHfl)-1000H 3 100-120 Viscousgel; soluble in water in the tolusulpllonate form. H3O /CH CH-CH CH-NH3O CHzCHCH2 TAB LE II Used N-elkyl-bis- C H2 C H2 H Used diisocyanateCompound 7 O CN(CH2)1N C O H C-N CHzCHzOL-I Compound 8 CH CHQOH OCN(CH2) NC O H;CCH2N CH-N oowcmnuoo Reaction temp, C.

Reaction time, hr. Remarks Add the dioxane solution dropwlse to ether.Filter the solid product by suction. Soluble in water in thetolusulphonate form.

3 dioxanc Add the dioxane solution dropwise to ether. Filter the solidproduct by suction. Soluble in water in the tolusulphonate form.

Distill oil the dioxane.

Soluble in water in the tolusulphonate form.

Distill off the dioxane.

Soluble in water in the acetate form.

3% dioxane 100 Distill off the dioxane. Soluble in alcohol/ water(20/80).

It has been found now that polymeric compounds containingN-alkyl-bis-alkylene-amino groups, and obtained by polycondensation of aN-alkyl-bis-w-hydroxyalkyleneamine with a dicarboxylic acid orderivative thereof e.g. an ester, acid chloride, or anhydride or with anorganic diisocyanate, are very suitable for substantially increasing thedevelopability and also the sensitivity of photographic silver halideemulsions on development in slow as well as in fast acting developers.

Polycondensation products, which have proved to be ery suitable in thatrespect, contain recurring units, which can be represented by:

L R ill.

wherein:

R represents an alkyl group of 1 to 5 carbon atoms e.g. methyl, eythl,propyl, isopropyl, .or a substituted alkyl group e.g. Z-hydroxyethyl, oran aralkyl group,

both alkylene or alkylene are alkylene groups containing from 2 tocarbon atoms, including alkylene groups substituted e.g. with a hydroxylgroup and/ or the carbon chain of which is interrupted by (a)heteroatom(s) such as oxygen, sulphur, or a substituted nitrogen atom,

n is a positive integer of at least 3, and

A represents a chemical bond or a NHgroup.

The compounds according to the invention in which A represents achemical bond can be prepared by condensing aN-alkyl-bis-w-hydroxy-alkyleneamine with a dicarboxylic acid orderivative of a dicarboxylic acid such as an ester, an acid chloride, orthe anhydride.

The condensations with the dicarboxylic acids are carried out withelimination of water either as such or by azeotropic distillation e.g.in toluene, anisol, or tetraline. The condensation with an ester of adicarboxylic acid is performed in such condition that the alcohol fromwhich the ester is prepared, is distilled oiT continuously during thepolycondensation reaction.

All techniques sufiiciently known from the polyester chemistry can beapplied in the preparation of these compounds. Care should be taken,however, that the ob tained condensation products are soluble in watereither in the basic form or in the salt form.

In general, both reagents are made to react in equimolar ratio, thoughan excess of one of them is not harmful in most cases.

Very suitable dicarboxylic acids and derivatives thereof are succinicacid and succinates, diglycollic acid and diglycollates, adipic acid andadipates, maleates and maleic anhydride etc.

Particularly suitable N-alkyl-bis-w-hydroxyalkyleneamines areN-alkyl-diethanolamines such as methyl-, ethyl-, propyl-, isopropyl-,and butyl-diethanolamine, N- alkyldipropanoliamines such asN-methyl-dipropanolamine, triethanolamine, triisopropanolarnine,N-a-methylbenzyl-diethanolamine etc.

By way of illustration some typical preparations of compounds accordingto the present invention are stated in Table 1. Compounds according tothe present invention in which A represents a chemical bond and in whichalkylene is substituted by a hydroxyl group, can be prepared bycondensing a 2,3:2',3-diepoxy-N-alkyl-di-propylamine with a dicarboxylicacid (e.g. the compound 6 from the Table 1).

Compounds according to the invention in which A represents a -NH-groupcan be prepared by condensing a N- alkyl-bis-whydroxyalkleneamine withadiisoyanate. The above mentioned N alkyl-bis-w-hydroxyalkyleneaminesare also particularly suited therefor. Very suitable diisocyanates arealiphatic diisocyanates e.g. hexamethylene diisocyanates. Aliphaticdiisocyanates in which the alkylene chain is interrupted by a heteroatom e.g. bis(2-isocyanatoethyl) succinate can also be used forpreparation of polyurethans suited for use according to the presentinvention. Generally, the polycondensations are performed in an inertsolvent such as benzene, dioxane etc. Uusually the reaction is continuedfor some hours at the boiling temperature of the solvent. Thepolycondensation product is separated either by precipitation with asolvent in which the polycondensation product is insoluble e.g. diethylether, or by evaporation of the solvent. By way of illustration sometypical preparations are stated in table II.

The development accelerators used according to the present invention canbe added as a base or in the salt form to the coating composition of asilver halide emulsion and/or can be incorporated into a water-permeablelayer, which applied under or on top of the emulsion layer forms awater-permeable system with the silver halide emulsion layer and thuscan come into effective contact with the silver halide.

The development accelerators can be incorporated into the coatedemulsion layer either by treating the emulsion layer with an aqueoussolution of these development accelerators or by coating this layer witha water-permeable layer containing the development accelerators, or alsoby bringing the development accelerators from a waterpermeable layerlying under the emulsion layer and comprising said developmentaccelerators into effective contact with the silver halide.

The water-soluble development accelerators can be added to thelight-sensitive silver halide emulsion during different preparationsteps of the lightsensitive material. For instance they can beincorporated therein as a separate addition either mixed with one ormore ingredients, which are used in the preparation of the silver halidegrains during the physical or chemical ripening process or anothermoment preceding the application of the emulsion.

The development accelerators are preferably added to the silver halideemulsion composition after the chemical ripening process and just beforecoating the emulsion.

The development accelerators are preferably added in dissolved form inwater or in an aqueous mixture of water and water-miscible organicsolvents that do not impair the photographic properties of thelight-sensitive silver halide emulsion. When the condensation productsare not sufficiently soluble in water in their base form they areconverted into the salt form by neutralisation e.g. with an acid such assulphuric acid, hydrochloric acid, p-toluenesulphonic acid, and aceticacid.

The optimum amount of development accelerator added to the silver halideemulsion depends on the very compound, on the nature of the colloidbinding agent for the silver halide grains, and on the amount and thekind of the silver halide in the emulsion. In general, however, thedevelopment accelerators are added to the light-sensitive material inamounts ranging from 100 mg. to g. per mole of silver halide. In thedeveloping bath they are normally used in amounts ranging from 0.1 to 10g. per liter. If necessary, these compounds can also be added in amountsexceeding these limits.

The step of increasing the sensitivity according to the presentinvention can be combined with a method known as chemical sensitization,in which together with the above-mentioned development acceleratorsusual amounts of chemical sensitizers are added to the silver halideemulsion, e.g., sulphur-containing compounds such as allylisothiocyanate, allylthiourea, or sodium thiosulphate, reducingcompounds such as the tin compounds described 1950 by GevaertPhoto-Producten, N.V., and 568,687 filed June 18, 1958 by GevaertPhoto-Producten N.V., the iminoaminomethane sulphinic acid compoundsdescribed in the British patent specification 789,823 filed Apr. 29,1955 by Gevaert Photo-Producten N.V. or noble metal compounds such asgold, platinum, palladium, iridium, ruthenium, and rhodium compounds. Asa matter of fact, the sensitizing action of the development acceleratorsused in the present invention comes in addition to the sensitzing actionof the sensitizing compounds originally present in gelatin.

The development accelerators applied in the present invention can alsobe used in combination with stabilizers and fog-inhibiting compounds forthe silver halide emulsion, for instance with mercury compounds ororganic sulphur-containing compounds that form an insoluble silver saltwith silver ions, preferably heterocyclic nitrogen-containing thionecompounds such as benzothiazolin- 2-thione and1-phenyltetrazolin-S-thione, the compounds described in the Belgainpatent specifications 571,916 and 571,917 both filed Oct. 10, 1958 byGevaert Photo- Producten N.V., and compounds of theoxytriazolopyrimidine type, e.g.5-methyl-7-hydroxy-s-triazolo[l,5-a]pyrimidine. The combination withsensitizing and stabilizing cadmium salts in the light-sensitivematerial as well as in the developing bath can also be applied.

Other compounds, which sensitize the photographic emulsion bydevelopment acceleration, such as organic onium compounds and polyoniumcompounds, preferably of the ammonium or snlphonium type, e.g.quaternary tetraalkylammonium salts, alkylpyridinium salts,bisalkylenepyridinium salts, alkylquinoline salts, andtrialkylsulphonium salts can be used together with thedevelopment-accelerators according to the invention in the developingsolution as well as in the light-sensitive material. Other ingredients,such as colour couplers, developing substances, hardening agents, andwetting agents can also be added to the emulsions in the ordinary way.

The development of low-sensitive as well as of highsensitive, offine-grain as well as of coarse-grain silver halide emulsions isaccelerated by the action of the above-mentioned developmentaccelerators. These products can 'be applied for accelerating thedevelopment of X-ray emulsions as well as of the most differentspectrally or non-spectrally sensitized emulsions. They can beincorporated into the photographic emulsion either with or withoutoptical sensitizers and can be used for increasing the sensitivity ofnegative emulsions as well as of positive emulsions.

The following examples illustrate the invention.

EXAMPLE 1 A washed negative gelatin silver bromoiodide emulsion (averagegrain size of the silver halide:0.8;t), the silver halide of whichconsists of 94.5 mole percent of silver bromide and 5.5 mole percent ofsilver iodide, is ripened at 45 C. The emulsion ready for coatingcontains per kg. 50 g. of silver halide, 75 g. of gelatin, 30 mg. ofoptical sensitizer with the following structural formula:

50 mg. of 5-methyl-7-hydroxy-s-triazolo[1,5-a] pyrimidine as astabilizer, and 500 mg. of saponine as a wetting agent.

This emulsion is divided into several aliquot portions and to theseparate portions is added one of the development accelerators asmentioned in the following Table 1. These emulsion portions areseparately applied to a cellulose triacetate support and dried. All teststri s are then exposed in the same conditions through a grey wedge anddeveloped for 7 min. at 20 C. in a fine-grain developer of the followingcomposition:

Water-800 ccs. Monomethyl-p-aminophenol sulphate-2 g. Hydroqhinone-S g.

Anhydrous sodium su1phite100 g. Borax-10 g.

Boric acid5 g.

Potassium bromide--0.5 g.

Water to 1,000 ccs.

The speed is represented by exposure values. A decrease in exposurevalue of -30 means a doubling in sensitivity.

TABLE 1 Amount of com- Sensitometric results pound per kg. Addedcompound of emulsion Fog. Gamma Rel. speed 0. 06 0. 60 104 Compound N o.1 0. 05 0. 61 g 0. 06 0. 64 84 Compound No. 2 100 mg 0. 05 0. 60 88 1 g0. 06 0.61 Compound No. 3 1 g 0. 08 0. 64 75 Compound No. 5." 1 0. 070.67 96 Compound No. 7 mg 0.07 0.65 80 1 0. 15 0. 61 72 Compound No. 850 mg 0. 07 0. 60 98 1 g. 0.08 0.71 91 Compound No. 9 100 mg 0. 06 0. 70

7 EXAMPLE 2 An emulsion as described in Example 1 is used, whichemulsion, however, is divided in aliquot portions respectivelycontaining the compounds mentioned in Table 2. The test strips, afterhaving been exposed were developed for min. at 20 C. in a classical fastacting p-N-methylaminophenol-hydroquinone developer of the followingcomposition:

Water-800 ccs. Monomethyl-p-aminophenol sulphate-2 g. Hydroquinone5 g.

Anhydrous sodium sulphite-ZS g. Crystalline sodium carbonate40 g.Potassium bromide1 g.

We claim:

1. Process for developing photographic materials containinglight-sensitive silver halide which comprises the step of developingsaid materials in the presence of a polymeric compound, containing thefollowing structural units or these units in salt form:

wherein:

R represents an alkyl group of 1 to 5 carbon atoms, an

aralkyl group, or a hydroxy-substituted alkyl group,

both alkylene and alkylene are alkylene chains containing from 2 to 10carbon atoms, including substituted alkylene chains and such chainsinterrupted by (a) heteroatom(s),

n is a positive integer of at least 3, and A represents a chemical bondor a NH-group.

2. Process for developing photographic materials containinglight-sensitive silver halide which comprises the step of developingsaid materials in the presence of a water-soluble polymeric compound inbasic or salt form and which is obtained in basic form by allowing toreact a N-alkyl-bis-w-hydroxylkyleneamine with a dicarboxylic acid orderivative thereof or with an organic diisocyanate.

3. A photographic light-sensitive silver halide material containing apolymeric compound containing the following structural units or theseunits in salt form:

L A ll 81.

wherein:

R represents an alkyl group of: 1 to 5 carbon atoms, an aralkyl group,or a hydroxy-substituted alkyl group, both alkylene and alkylene arealkylene chains containing from 2 to 10 carbon atoms, includingsubstituted alkylene chains and such chains interrupted by (a)heteroatom s) n is a positive integer of at least 3, and

A represents a chemical bond or a NH-group.

4. A photographic light-sensitive silver halide material according toclaim 3 containing said polymeric compound in an amount ranging from mg.to 10 g. per mole of silver halide.

References Cited UNITED STATES PATENTS 4/1964 Grabhofer et al 96 -66.33/1967 Julius Thiers et a1. 9666.3

U.S. Cl. X.R.

